This invention relates to a process for the simultaneous removal of H.sub.2 S, SO.sub.2 and elemental sulfur from gaseous mixtures by treating the gaseous mixture with a solvent. The solvent, after having been saturated with the components to be removed, is regenerated and reused.
Such a process is disclosed, for example, in DOS 2,931,046. This is employed primarily to remove high proportions of elemental and bound sulfur from the waste gases of plants operating by the Claus process. In these plants, hydrogen sulfide is converted into elemental sulfur for the manufacture of sulfur. Typically, the removal of elemental and bound sulfur is attained by admixing the aqueous scrubbing medium, i.e., solvent, with specific types of catalytic solids in finely divided form. More particularly, the gaseous waste stream is brought into intimate contact with an acidic, aqueous suspension of finely divided catalytic material such as aluminum oxide or active carbon. The acidity of the suspension is of the kind produced by absorption of acidic components from the gaseous stream. The formation of colloidal sulfur in the aqueous phase is prevented by adding the catalytic solid materials. The sulfur is thus deposited on the finely divided catalytic solids and can be removed therefrom by regeneration of the catalytic solids. In order to regenerate the catalyst, the finely divided material is separated from the aqueous medium and rinsed with a liquid solvent for sulfur, or with a gas inert to the material at temperatures effective to remove the sulfur by dissolution or melting. The thus-regenerated material is thereafter recycled in the form of an aqueous suspension.
By the use of this known method, sulfur, in substantially all its various forms, is effectively removed from a gaseous stream. However, a disadvantage of the process resides in that the regeneration of the catalyst slurry employed is very expensive.